Grit collector



M y 28 1 40. Y c, s. WILEMAN 2,202,415.

GRIT COLLECTOR '8 Sheets-Sheet 1 Filed March 10, 1937 May 28, 1940.

' c. s.- WILEMAN GRIT COLLECTOR Filed llarbh 10. 1937' s Sheets-Shet 2 V F l I c. s. WILEMAN 2,202,475

GRIT COLLECTOR Filegl March 10, 1937 8 Sheets-Sheet 3 May 28, 1940. I c. s. WILEMAN 2,202,475

GRIT COLLECTOR,

Filed larch 10. 1937 8 Sheets-Sheet 4 May 28, 1940. c. s. WILEMAN GRIT COLLECTOR Filed hrch 10, 1937 8 Sheets-Sheet 5 1223222502 razz'md'fizemare M r-72ers May 28, 1940- c. s. WILEMAN GRIT COLLECTOR Filed larch 10. 1957 8 Sheets-Sheet 1 May 28, 1940. c; s, WILEMAN 2,202,475

GRIT COLLECTOR Filed latch 10, 1937 a Sheets-Sheet a Patented May 28, 1940 UNITED STATES v PATENT OFFICE onrr COLLECTOR Croaier S. Wilcman, Chicago; Ill., assignor to Link-Belt Company, Chicago, 11L, a corporation of Illinois Application March 10, 1931, Serial No. 130,010 15 Claims. (01. 210-3) stream of sewage material and may be subse-' quently washed and separated from lighter organic material, the organic material being retained in the stream of sewage, the washed grit being discharged from the system.

My invention is adapted to provide means for accomplishing the above purpose and doing it in such a way that change in rate of flow and change in the character of the sewage will have a minimum efiect upon the operation of the device. f I

Other objects will appear from time to time throughout the specification and claims.

My invention is illustrated more or less dia-.'

grammatically in the accompanying drawings wherein r Figure 1 is a planview of one form of my device;

I Figure 2 is a section along the line 2-'--2 of Figure. 1; e

Figure 3 is a section along the line 3-3 of Figure 2; r

Figure 4 is a section along the line 4-4 voi Figure 2; a

Figure 5 is a section along the line 5-5 of Figure 2; a

Figure 6 is a partial plan view of a modified form;

Figure '7 is a section along the line 1-1 oi- Figure 6;

Figure 8 is a section alongthe line 8-8 of Figure '7;

Figure 9 is a section'similar to Figures2 and 7 showing-a modified form; V v I k Figure 10 is a section through the periphery of the tank showing a modified form;-

Figure 11 is a detail of a modified-form. of

center column;

Figure 12 is a plan view of a modified form of the device wherein a rectangular tank is used; Figure 13 is a section along the line li -II of Figure 12;

Figure 14 is a section along the line ilk-l4 of Figure 16 is a plan view of a further modified form; Figure 1'! is a section along the line l1-l'l of Figure 16 illustrating the floor of the tank of constant inclination throughout;

Figure 18 is a section along the line lt-lt of Figure 17;

Figure 19 is a view similar to Figure 18 show- 5 a ing a modified form where a single grit washing 'screw is used.

I is a cyclindrical tank having a weir 2, surrounded by an e'fliuent trough '3, which in turn is surrounded by a boundary wall 4, carrying a 10 T-rail 5. Extending outwardly from the boundary wall 4 is a drip trough 6, which drains into the efliuent trough 3 through passages Oil in wall I 4. 1 is a grit bin. 8 isan emuent pipe connected to the efiluent trough 3. The floor of the tank 16 is generally conical and inwardly and downwardly inclined from the' periphery. In the form shown, the outer portion of the floor oi the tank at 9 is less steeply inclined than the central portion l0. II is a hollow infiuent column extending 20 upwardly from the center of the tank receiving sewage from the infiuent pipe I! and discharging through openings litothe tank at a point below the water level. This column extends upwardly and carries a ball pivot I4. 25

20 is a bridge pivoted at one end on the ball pivot and supported by track engaging antifriction wheels ii at the outer end traveling along the rail I. The bridge carries a walkway 22 Y and is provided with a handrail 23. 24 Ba 30 motorized gear reducer on the end of the bridge having a sprocket wheel 25 over which travels the endless chain 28 which chain encircles the tank lying in the eiiluent trough I. 21 is a guide wheel carried by the bridge. This wheel guides 35 and supports the chain as it is drawn from its position in the eiiluent trough up over the sprocket 25 to cause movement of the outer edge of the bridge along the periphery of the tank.

30 is a combined grit washer and screw con- 40 veyor supported from'the bridge in inclined position; terminating at its inner end adjacent the foot of the column ll, extending at its outer end beyond the peripheral wall 4, and'overhanging the drip trough. The axis ofthis screw conveyor 4 is generally parallel with the surface of the sharply inclined floor oi the tank l0 but rises above the less sharply inclined fioor 9. This screw washer and conveyor is driven by a pair of mitre gears SI and chain 82 from the motor-'- Y 4 to communicate with a hopper 34 having a gate 58 35. 38 is a discharge trip for the hopper gate located within the grit bin I so thatas the bridge goes around carrying the hopper withit the gate is opened when it is in register with the grit bin so as to discharge the grit therefrom. to the bin.

The outer periphery of the floor .oi the tank indicated at 9 is not suflicientiy inclined to cause flow of settled material downwardly so a pin-- rality of scrapers 48 are provided carried by the bridge their function being to plow or scrape the deposited sludge toward the center of the tank and toward the sharply inclined trough I8 where it can travel by gravity downwardly into the path of the screw conveyor and washer 38.

4| is a grit plow adjacent the screw conveyor and immediately behind it so that all sludge deposited on .the floor I8 will be conveyed forwardly along a tangential path and held within the zone of influence of the screw.

The screw is rotated at a rate 01 speed sufficient to insure that sludge comprising largely heavy grit or inorganics with some adhering light organics will be propelled tangentially by the plow 4|, and be conveyed along the floor I8 upwardly to the trough 33 and thence discharged to the grit bin. The rate of rotation of the screw is such as to furnish a churning or agitating efiect at the point oi. emergence so as to wash organics from the inorganics allowing these lighter particles to flow or float back into the tank. Any heavy organic or floatable material which may have been trappedwith the settling grit is agitated by the screw and thrown back into suspension to be carried away by the liquid in the tank.

The organics are prevented from settling, not primarily by the rate 01 flow of the current in the tank but by the agitating eilfect resulting from the movements of the bridge, the scraper, the screw and the grit plow as they travel about the periphery of the tank. The rate of travel is kept high enough so as to insure constant agitation at a rate sufficient to prevent the settling of the light organics while not sumcient to interfere with the settling out of the heavy inorganics or grit. In the modified form shown in Figures 6, 'l and 8, the only difference between thedevice shown in Figures 1 to 5 is that the bridge 58 is substituted for the bridge 28, this bridge being Y-shaped in cross section to permit positioning of a flight conveyor in place of the screw conveyor 38. The flight conveyor comprises a chain 5| traveling about sprockets 52, 53 and 54 having flights 55. These flights scrape the material upwardly along the floor I8 and along a trough 58 according to the same general principle as the screw conveyor 38.

Figure 9 is a further modified form wherein there is substituted for the screw conveyer or the flight conveyor a reciprocating conveyor comprising a. frame 68 suspended on stirrups 5|, having conveyor blades 62. The stirrups are supported by links 83, 64 on bell crank levers joined by a link 88 and reciprocated within the connect ing rod 68 by cams in the housing 51 driven by the speed reducer. Figure 10 shows in section a modified form of tank wherein a grit discharge chute I8 carried by the bridge discharges into a deeper grit and drip trough 'II, communicating at both ends with the grit bin 1. A scraper I2 is carried by the bridge and pushes the grit around the trough to discharge it into the grit bin. Figure ii is a detail section through the cento travel respectively along the tracks I81.

deposit by a wiper blade 85 supported on abracket 81 on the bridge 28.

The purpose of having the tank with a floor of two different slopes is to permit reduction in the depth of excavation necessary but if desired the scrapers 48 may be omitted and the floor of thetank would then be made with the same slope throughout and the trough 33 could commence adjacent the eiliuent weir rather than adjacent the break between the two angles of the floor. This floor arrangement is shown in connection with a diilerent type of tank in one 01' the other modified forms of the device.

In the modified form shown in Figures 12 to 15, IM indicates a rectangular tank having a V-shaped bottom, one side of which I82, is so sharply inclined that there will be no appreciable deposit of sludge thereon, the sludge sliding by gravity freely down therealong; the other part of the bottom or floor I83 is less sharply inclined.- Associated with the sharply inclined floor Il3 is a still less sharply inclined floor I84 adapted to support sludge which may be deposited thereon. The tank is' bounded by longitudinal walls I85, I86 which carry tracks or rails I81 and bounded by end walls I88. plied with sewage through the channel III and discharging sewage into the tank at a point be-- low the water level through the apertures III.

H2 is an emuent trough associated with a weir H3 and discharging through an emuent channel H4. H5 is a drip trough carried on the wall I86 draining through ports 8 in wall I85 into the eiliuent trough H2. III, III are floor panels adjacent the walls I88 also sharply inclined downwardly so as to permit free flow by gravity of the sludge.

III is a bridge extending from end to end of the track having anti-friction rollers I22, adapted I23 is a motorized speed reducer driving a longitudinal shaft I24. On this shaft are drums I25 about which are wound cables I25, I 21, the cables being anchored respectively at their ends on the walls I88. I28 is an electric cable anchored on thewall I88 and'wound about a spring reel I 29 whereby electric currentis brought to the bridge. The motor of the motorized speed reducer I23 is automatically reversible so that as are not illustrated.

Suspended on the bridge I2I is .a screw conveyor I38. Its axis is generally'parallei with the floor I 83. -It is enclosed in a trough I 3I which extends upwardly from the floor I83 across the wall I88 and communicates with a grit hopper I32 having a gate I33 adapted to discharge into the grit bin II6 when the gate is opened by the gate opening stop I34. The screw conveyor 'is driven from a motorized speed reducer I35 by means of a chain drive I 33 and the mitre gears I31. It will be understood that there are a pair of these screw conveyors, each in a separate trough both adapted to operate in unison. I38, is a grit plow interposed between the two con- I88 is an influent trough sup- 1 basis" .veyors and adaptedito. travel along the door the tank. i

Also mounted on the bridge are a pair oi flight conve rscom risin chains ill, flights ill, the w ,0 p 8 such as tops-event thesettllng out oi lighter,

5 chains traveling over sprockets 2', I, l. The sprockets I are driven by. a chain drive I from the motorized speed since thereis one conveyor on eachside ofthe 9 bridge, these conveyors scrape sludge across the floor ill into the hopper formed between the floor I, II! and H1 and in whichever direction the bridge is moving, the, leading. flight conveyor scrapes the freshly deposited sludge down into. the hopper where it can be picked up-by theapiow' and the screw conveyors andconveyed upwardly, washed and discharged as in the previously discussed figures.

In the modified iorm shown-in Figures 16, 17 .0 and 18, the rectangular tank has merely the two inclined floors ill and Ill Two screw conveyors I are supported on the bridge ill and the flightconveyors are omitted. In this case. each screw conveyor comes clear to one end of the tank and does its work on the sludge in the tank without the interposition of the flight conveyor. the tank floor being such that all the sludge comes intov the zone of influence of the screw conveyor and washer.

' In the modified form shown in Figure 1'9 but a single screw conveyor I" is used and it is associated with two grit plow blades III, I! supported on the brid e mounted on a rocker arm I54 with a trip m hanism adaptedto trip the rocker arm at each end of its excursion, so that the grit plow is always on the rear side of the screwconveyor. The details of this trip mech-- anism are not shown as it forms no part of the present invention andis a standard'engineering C product. I

In a grit washer of the type here disclosed where the influent reaches the tank at the center and discharges along radial lines to the periphery and over a peripheral weir, the influent' velocity 45 at the center is high and progressively decreases toward the periphery, at the center the flow velocity. is sufllcient to sustain the organics. At'the periphery the flow veloc ty is insuillcient to "sustain' organics. The flow velocity throughout is insuiilcient to sustain or prevent thesettiing of the inorganic grit.

The combined collector grit washer and"agitation structure as it travels around the tank has its linear velocity at a maximum at the periphery.

decreasing at the center so that in that nart'of.

A the tank where flow velocity is not suiilcient to prevent sedimentation of the organics, the agitating effect'supplenients or substitutes for flow velocity. At the center where the velocity of flow 60 is high enough, the relatively low linear speed 01'- the agitation makes no diiierence.

The weir which controls the levelof liquid in the tank is subject to unsightly entrapment. 01

solid organic material and so I provided a scraper I68 carried by the agitator and engaging the weir to scrape, of! and displace any organic material which may otherwise be caught and remain to be unsightly or to create a nuisance. A

I have shown in my specification and drawings 70 a number of modified forms of the device with different shapes 0! tank, different types ofconveyor and washer and various different combinations. Of course, many other combinations 'of these same elements" or diflerent elements might 15 he adopted without departing materially from the reducer III; 'Ihese' flight conveyors travel along the surface Ill and possible agitation resulting from the ilowoi liquid spirit 'o rmy invention and wish I, therefore. that myflshowing' beregalh asiiasensedin ma 0. 4

IngeneralIproposethattheagitationwillbe' organic solids, while permitting settling out of 'heavierorganlc This must'beregarded, of cours .as a general line or demarcation.

There may-be organic solidswhich will settle, thereinay be inorganic solids'which will not 10 settle. Even some lighter inorganic solids may becarrieddownwiththe'heavierandsettleiand the general proposition is that the division line isbetween certain heavy-solids'and certain'light solids, and the heavy solids are to be disposed oi I in oneway and thelightsolidsinanother..-'

Iclaim: LMeans-ior separating heavy irom iouid containing both heavy and-light solids,

comprising a settiing'tsnk'sdapted to contain the liquid to be treated, means, for positively agitating" the entire body of the liquid to prevent settlement of the lighter solids, means for collecting the heaviersettled' solids, means for agitating the liquid and heavier solids to wash the li hter solids from the-heavy.and means for discharging the heavier solids nomthe system while re- "taining the lighter solids in the liquid, said means including a combined agitator and conveyor and means for propellingit bodily through the liquid .9

- at a'rate oi speed such that the entire'body oi liquid in the tank is mitintsined in a continuous 7 state of agitation substantially greater than any through the 2. Means for separating heavy solids from liquid containing both heavy and light solids. comprising a settling tank adapted to contain the liquid to be treated, means, for positively agitating the entire body' of the liquid to prevent settle- 40 ment of the lighter solids. means for collecting I the heavier settled solids, means for agitating the liquid and heavier solids to wash the lighter solids from the heavy, and means for discharging the heavier solids from the system while retaining the lighter solids in the liquid, said means including acombined agitator and conveyor and means for propelling it bodily through the liquid at a relatively high rate of speed and means independent of its bodily movement for operating it to convey 'and agitate material.

3, Means for separating heavy solids from liquid containing both heavy and light solids, comprising a settling tank adapted to contain the liquid to'he means, for positively agitating the entire body of the liquid to prevent settlement of the lighter solids, means for separately collecting the heavier settled solids, for

agitating the liquid and heavier solids to wash the lighter solids from the heavy, and means for discharging the heavier solids from the system while retaining the lighter solidsin the liquid,

said means inchlding a combined agitator and conveyor partially immersed in'the liquid in the tank and extending upwardly therefrom toward the periphery of the tank and means for propells I ing it bodily through the liquid at a rate of speed such'that the entire body of liquid in the tank is maintained in a continuous state of agitation substantiallygreater than any possible agitation resulting from the flow of liquid through the tank.

4. Means for separating heavy solids from liquid containing both heavy and light solids, comprising a settling tank adapted to contain the liquid to be treated, means, for positively agitat- I6 ing theliquid to prevent settlement of the lighter solids, for collecting the heavier settled solids, for

agitating the liquid and heavier solids towash the lighter solids from the heavy, for retaining the lighter solids in the liquid and for discharging the heavier solids from the system, said means including a combined agitator and conveyor partially immersed in the liquid in the tank and extending upwardly therefrom toward the periphery of the tank and means for. propelling it bodily through the liquid at a relatively high rate of speed .to agitate the iiquid, and means independent of its bodily movement for operating it to convey and discharge material.

5. A grit chamber for sewage plants comprising a circular tank having an inclined floor, a centrallydisposed influent port, a peripheral eiiluent weir, a combined grit washer and conveyor exthe liquid in the tank and discharge the sludge from the system 6. A grit chamber for sewage plants comprising a circular tank having an inclined floor, a centrally disposed influent port, a peripheral efliuent weir, a combined grit washer and conveyor extending from the center toward and across the eflluent weir means for propelling the conveyor bodily along the periphery to collect settled sludge and agitate the liquid in the tank and for operating the conveyor to propel settled sludge radially, wash the sludge at the point of emergence from the liquid in the tank and discharge the sludge from the system, the conveyor being substantially I parallel with the central portion of the tank floor and inclined to the outer portion thereof.

7. A grit chamber for sewage plants comprising a circular tank having an inclined floor, a centrally disposed influent port, a peripheral eflluent 5 tending from the centertoward and across the,

weir, a combined gritwasher and conveyor exeflluent weir, means for propelling the conveyor bodily along the peripheryto collect settled'sludge and agitate theliquid in the tank and for operating the conveyor to propel settled sludgeradially, wash the sludge at the point of emergence from theliquld in the tank and discharge the sludge from the system, the conveyor being substantially parallel with the central-portion oi the tank door and inclined to the outer portion thereof, scrapers carried by the conveyor adapted to agitate and propel sludge settled on the peripheral portionof the floor of the tank centrally and discharge it to the central portion of the tank where it may be picked up by the conveyor.

8. A grit chamber for sewage plants comprising a circulartank having an inclined floor, a centrally disposed influent port, a peripheral eflluent weir, a combined grit washer and conveyor/extending from the center toward and across the eiliuent weir, means for propelling the conveyor bodily along the periphery to collect settled sludge and agitate the liquid in the tank and for operating the conveyor to propel settled sludge radially, wash the sludge at the point of emergence from the liquid in the tank and discharge-the sludge from the system, the conveyor comprising a shaft having a spiral flight thereon, aradial sludge plow associated with the flight and a trough enclosing that part of the conveyor which extends over the weir.

9. A grit chamber for sewage plants comprising a circular tank having aninclined floor,a centrally disposed influent port, a peripheral eflluent weir, a combined grit washerand conveyorextending from the center toward and across the eilluent weir, means for propelling the conveyor bodily along the periphery to collectsettled sludge and agitate the liquid in the tank and for operating the conveyor to propel settled sludge radially, wash'the sludge at the point of emergence from the liquid in the tank and discharge the sludge from the system, a grit bin outside the periphery of the tank, a hopper into which the conveyor discharges and means responsive to-the movement of the conveyor for opening the hopper to cause it to discharge into the grit bin when it is in register therewith. Y

10. In combination, a circular sedimentation tank, means for introducing solids bearing liquid .means along the eiiiuent zone whereby the linear rate of travel and the agitating ei'fect resultant therefrom increases radially from the influent toward the effluent zone, the agitation resulting from the rotation of the mechanical means only being insufliclent to hold solids in suspension adjacent the influent zone but suflicient to hold solids in suspension adjacent the eiiiuent zone.

11. In combination, a circular sedimentation tank, a circular weir surrounding it, an agitating and conveying member rotating about a center concentric with the weir and traveling along the weir anda scraper carried by the conveying member and traveling along and cleaning the weir.

12. The method of controlling the gravltal separation of suspended solids from liquids which consists indischarging. a stream of liquid containing solids in suspension into a settling zone, causing the liquid to flow radially outwardly from the point of entrance into said zone whereby the velocity of flow decreases gradually and uniformly from a maximum adjacent the influent point where it is sufllcient to maintain solids in suspension to a minimum adjacent an efiuent zone where the velocity is insufficient to hold solids in suspension and in imparting to the mass of liquid, independent of the rate of flow thereof an agitation increasing gradually in the direction of liquid flow from a minimum adjacent the influent point to a maximum adjacent the eilluent zone and adjusting such rate of imparted agitation with respect to the flow rate that the imparted agitation plus the flow rate is suflicient throughout the entire liquid mass to uniformly maintain lighter solids in suspension while permitting heavier solids to settle out.

13. In combination, a circular sedimentation tank, means for introducing liquid containing solids in suspension to the tank adjacent the center thereof and for withdrawing the liquid from the tank about much of the periphery thereof, the rate of flow of liquid in the tank from the center of the periphery decreasing from a maximum adjacent the influent zone suflicient to hold of, upwardly inclined from beneath the liquid level adJacent the center to above the liquid level adjacent the periphery, means for rotating said conveyor about its longitudinal axis and for revolving the conveyor about the central axis of the tank, means associated with the ,conveyor tending to hold much of the material presented to it in juxtaposition therewith during its revolving movement whereby both the revolving and the rotation of the conveyor cooperate to agitate and wash settled solids presented to the conveyor.

14. A grit chamber for sewage plants comprising a circular tank having an inclined floor, a centrally disposed influent port, a peripheral eflluent weir, a combined grit washer and conveyor extending from the center toward and across the diluent; weir, means for propelling the conveyor bodily along the periphery to collect settled sludge and agitate the liquid in the tank and for operating the conveyor to propel settled sludge radially, wash the sludge at the point 01 emergence Irom the liquid in the tank and distravel along the floor oi the tank and a radial scraper adapted to be rotated about the tank with the conveyor behind the conveyor flights.

15. A grit chamber for sewage plants comprising a circular tank having an inclined floor, a centrally disposed influent port, a peripheral eflluent weir, a combined grit washer and conveyor extending from the center toward and across the eflluent weir, means for propelling the.

conveyor bodily along the periphery of the tank to collect settled sludge and agitate the liquid in the tank; means for operating the conveyor to propel settled sludge radially, a part of the conveyor being adapted to wash thelsludge at the pointoi emergence from the liquid in the tank and to discharge the sludge from the system, the conveyor comprising a plurality of reciprocating blades, means for bringing them into engagement with the floor oi the tank, moving them outwardly, lifting them ,and returning them toward the center of the tank out of contact with the floor.

CROZIER S. WILEMAII. 25 

